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Paper | Special issue | Vol 79, No. 1, 2009, pp.471-486
Published online, 11th August, 2008
DOI: 10.3987/COM-08-S(D)4
Subtle Control in Solution and Crystal Structures with Weak Hydrogen Bonds: the Unusual Profile of Dimethyl 3, 12-Dioxo-7, 8 Dithia 4, 11-Diazabicyclo[12.2.2]octadeca-1(16), 14, 17-triene 5, 10-Dicarboxylate (TDA1)

Isabella L. Karle,* Lulu Huang, Punna Venkateshwarlu, A. V. S. Sarma, and Subramania Ranganathan

*Laboratory for the Structure of Matter, Naval Research Laboratory, Washington D.C. 20375-5341

Abstract

The structural features of the title compound were determined or examined by three diverse procedures: single crystal X-ray diffraction analysis, solution spectroscopic procedures and quantum mechanical theoretical calculations. The conformational asymmetry of the macrocycle provides the opportunity to form one strong N-H···O-C intermolecular hydrogen bond, as well as, a number of weak C-H···O-C bonds. The interior of the macrocycle has short approaches for N-H···π and N-H···S. The many weak hydrogen bonds cooperate to form a very hard, robust crystal. Crystal parameters: C18H22N2O6S2, P212121, a = 5.108(1) Å, b = 18.948(4) Å, c = 21.029(3) Å, α = β = γ = 90°. Quantum chemical calculations have provided a strong foundation for weak hydrogen bonds. Contrary to popular belief, the present work has conclusively proved that the importance of weak hydrogen bonds is perhaps underestimated.